Crosswind deflection element for preventing sedimentation

ABSTRACT

The invention relates to a crosswind deflection element ( 10 ) for assembly on open ground for the specific reduction or prevention of a deposit of snow, air-borne sand or the like, with a baseplate ( 1 ) at the bottom, for anchoring into the ground, with a central post ( 2 ) rising up from the baseplate ( 1 ) and with a plurality of guide plates ( 3 ) mounted on the post ( 2 ), wherein the guide plates ( 3 ) are provided projecting in vertical orientation in cruciform manner on the post ( 2 ) and the length of the guide plates ( 3 ) increases from the baseplate ( 1 ) upward.

The invention relates to a crosswind deflection element with the features of the preamble of claim 1 that is intended for being set up in the open country, in particular at critical places exposed to strong winds, such as crests or the like. The occurrence of strong crosswinds at such places in the country often results in a deposit of solid material carried along by the air, such as wind-borne sand or snow. In the winter, at crests, for example, such snow deposits can become dangerous, because they may lead to the formation of snow avalanches if the deposits are not systematically removed, for example by repeated blasting operations. However, routine blasting operations carried out in order to remove dangerous snow overhangs in the mountains are costly and time-consuming and not always sufficient in order to effectively prevent the formation of avalanches.

In the prior art, so-called snow fences have among others been used to influence the undesired accumulation of snow caused by the wind. The fences set up at critical places in the country systematically cause an accumulation of snow in order to prevent snow or wind-borne sand, for example, from being blown onto a street or the like. However, such fences are not appropriate to effectively prevent an accumulation of solid material present in the air and carried along by strong crosswinds, a so-called sedimentation, under all circumstances. The other conventional avalanche protection elements proposed in the prior art, which are intended for being set up at critical places in the mountains, either involve the deviation or the breaking of snow or debris avalanches that have been set off. That means, they are not appropriate for systematically preventing the formation of such debris or snow avalanches.

Starting from this prior art, it is the object of the present invention to provide a crosswind deflection element for an assembly in the open country, by means of which a deposit of solid material from the air can systematically be prevented. Furthermore, the crosswind deflection element according to the invention should be as easy to manufacture and assemble in the country as possible.

This problem is solved by a crosswind deflection element with the features of claim 1. Advantageous embodiments and further developments of the invention are subject matter of the dependent claims.

The crosswind deflection element according to the invention, which is provided for being set up in the open country in order to systematically prevent a deposit of snow, wind-borne sand or the like, comprises a baseplate at the bottom for anchoring into the ground, a central post rising up from the baseplate, as well as a plurality of guide plates mounted on the post for deflecting the wind, and is characterized in that the guide plates are provided projecting in vertical orientation in a cruciform manner on the post, and that the length of the guide plates increases from the baseplate upward. Thus, the guide plates of the crosswind deflection elements, which systematically catch and deflect the wind, are provided such that they project in vertical orientation from the post so that they provide a contact surface for occurring crosswinds, which is as large as possible. The length of the guide plates is shorter in the lower region and increases from the lower region upward, so that a trapezoid shape is formed, the width of which is larger at the upper end than at the lower end of the crosswind deflection element. All guide plates are mounted on a central post rising up from the baseplate such that the crosswind deflection element can be mounted in a self-supporting and freestanding manner without the need of additional stay ropes or the like. For mounting and setting up the crosswind deflection element according to the invention, a baseplate is provided at the bottom, on which the central post is firmly mounted. The baseplate serves for setting up and anchoring the element in the ground at places in the country where it is desired to systematically prevent a deposit of solid material carried along by the air. Due to the fact that the guide plates become longer toward the upper side, the surface of the crosswind deflection element, which opposes the striking wind, increases toward the upper side. As a result of this inventive measure, the crosswinds are caught in a systematic and enhanced manner and are in a kind of nozzle effect guided downward by forming intensified swirls. These intensified swirls in the area of the crosswind deflection element effectively prevent the deposit of solid material from the air, such as sand or snow. When the crosswind deflection element according to the invention is set up at critical places in the mountains, such as at crests or hilltops, the formation of avalanches due to undesired local deposits can be prevented with comparatively simple means, as the solid material carried along by the wind does not accumulate at places where the crosswind deflection elements are set up, but are swept away by the systematically deflected wind. The crosswind deflection element according to the invention thus prevents with a construction comparatively simple in design the formation of undesired deposits (sedimentation) in the open country, no matter whether these deposits are deposits of wind-borne sand or snow deposits. The crosswind deflection element according to the invention can preferably be set up in groups of several crosswind deflection elements of this kind at respective places in the country, which are problematic in view of strong winds. Due to the central post, each of the elements as such is extremely robust and can be set up in a freestanding manner. Consequently, the installation and the assembly of the crosswind deflection elements are comparatively simple, as only the central post requires a preinstalled foundation or a counter plate in the ground.

According to an advantageous embodiment of the invention, the guide plates for the deflection of the crosswinds are arranged at predetermined spacings from each other at the post such that a row of permeable clearances is formed between the guide plates. The wind guide elements of the crosswind deflection element, which are formed by the guide plates, are thus provided over a comparatively large area, but provide a certain kind of permeability due to the clearances. On the one hand, this is advantageous in that the elements do not form a solid barrier over the whole surface and are interrupted by clearances that allow a person to see through the elements. The intervention into nature is thus comparatively small. On the other hand, due to the clearances between the guide plates, the elements are less susceptible to damage as a result of very strong winds that often occur particularly in the mountains. Consequently, a long-term assembly and stability of the elements is guaranteed. According to an advantageous aspect in this regard, the width of the clearances can in particular be half the width of the guide plates such that still a sufficiently large deflection area for striking winds is guaranteed, which leads to the formation of swirls on the ground due to the nozzle effect and guarantees a secure prevention of a local sedimentation.

According to another advantageous embodiment of the invention, the guide plates are at least at their free ends coupled to each other such that they form four sail-like wind guide elements that project in a cruciform manner from the post. Thus, the guide plates, which consist of single elements, are securely connected and coupled with each other such that they form in spite of their permeability a common and stable component for the purpose of a systematic deflection of winds. The single guide plates may, for example, be coupled by a rigid connection, such as a welding with rods or profiled elements. Alternatively, the coupling may be carried out by flexible elements, such as wire ropes or the like. The guide plates, which are coupled with each other, respectively project in a cruciform manner from the central post and form some kind of a trapezoid sail having a larger width at the upper end of the element than on the bottom side.

According to another advantageous embodiment of the invention, upper and lower cross members, which project from the post in a cruciform manner, are provided for retaining and additionally securing the guide plates. When such upper and lower cross members, which project from the post in a cruciform manner, are given, the laterally protruding guide plates can be mounted in a safe and fixed manner, without the weight of the whole element being strongly increased. For the guide plates may be provided in the form of very thin sheet metal, for example, which itself does not have a high inherent stability, but which has in connection with the cross members, which may, for example, be provided in the form of profiled tubes, the necessary rigidity in view of impinging winds, even in the case of strong winds. The mounting and the assembly of the guide plates between the cross members can be carried out in different ways: by a fixed welding to longitudinal bars, by inserting the guide plates into recesses, by a mounting by ropes stretching between the cross members, or the like.

According to another advantageous embodiment of the invention, the baseplate, on which the post is mounted so as to rise vertically upward, is realized in a two-piece form and is provided with an installation aid, preferably a plug-in system of the type pipe-in-pipe. The baseplate can, for example, consist of a first member plate and a second bottom plate, the member plate being firmly connected to the post and the bottom plate being provided for being installed in the ground. The bottom plate can be made of a metal material and/or a combination of a metal and a concrete material such that a secure foundation for the crosswind deflection element to be set up is provided. According to the invention, an installation aid, for example in the form of a plug-in system of the type pipe-in-pipe, is provided for the mounting: to this end, the bottom plate comprises, for example, a pipe of a smaller diameter, onto which the pipe of a somewhat larger diameter of the post of the crosswind deflection element can simply be slipped on from above. Thus, already upon the first installation of the crosswind deflection element, the position is securely fixed, and for the assembly the two plate elements of the baseplate must only be screwed together, for example. This enhances in particular a mounting in rough terrain through the air by a helicopter. Only one single worker is required on the ground. Furthermore, the necessary intervention into nature is minimal.

According to a further advantageous embodiment of the invention, the guide plates or the four wind guide elements formed of the guide plates are respectively additionally secured to upper and/or lower strut members at upper and/or lower ends of the post. The strut members can, for example, be realized by ropes or rods extending diagonally from a free end or a center portion of the guide plates or the cross members to the central post. By means of such strut members, the stability and the resistance to striking winds is further increased. Thus, without a strong increase in the weight of the element, a very robust construction for the purpose of a deflection of winds can be obtained. For example, the strut members can be made up of stretched wire ropes that are attached to connecting flanges. However, in the present case, the strut members may also be realized in a fixed manner, for example by welded rods. It is a further advantage of the compact and comparatively simple construction of the crosswind deflection element that the crosswind deflection element may be mounted in the country in a free-standing manner, i.e. no disturbing lateral anchorage by wire ropes or the like is required that would require several anchorage points and concrete foundations or the like, respectively.

According to a further advantageous embodiment of the invention, the guide plates, which catch and deflect the wind, consist of sheets of a metal material that are in the longitudinal direction profiled or corrugated. In this manner, the guide plates may be manufactured from a comparatively thin sheet material and are thus very lightweight. All in all, this leads to a lightweight structure of the entire crosswind deflection element, which is an advantage, in particular when it needs to be transported by a helicopter in order to be set up in rough terrain. Furthermore, the guide plates with profiles or reinforcing ribs in the longitudinal direction are sufficiently stable so that a deformation due to strong winds can be prevented.

According to a further advantageous embodiment of the invention, the guide plates are rigidly mounted in a respective circumferential frame that itself is attached to the post. The four guide plates protruding laterally in a cruciform manner given by way of example are thus fixedly assembled within a frame, respectively, and form a compact unit. The frame may consist of welded profiled tubes and increases the stability and the rigidity of the element. The guide plates themselves are securely fixed in their respective frames at the desired position. The mounting of the frame itself on the central post can be realized in a detachable manner by screw connections with respective flanges or the like, for example.

According to a respective alternative embodiment of the invention, the respective guide plates of a group of guide plates, which form a common wind guide element, are connected to each other and secured in their position by coupling ropes between upper and lower cross members. For example, a first coupling rope may be stretched between an upper and a lower cross member at the free end of the guide plates, and in the center portion there may be one coupling rope or several coupling ropes, which respectively hold the guide plates in the four directions and in the desired vertical orientation.

According to a further advantageous embodiment of the invention, an anti-rotation device is provided for an installation of the element that is secure against rotation. An anti-rotation device may, for example, be realized by a pin or a stud at the bottom plate that engages into a respective borehole. Other anti-rotation devices are also possible. The anti-rotation device is advantageous in that the crosswind deflection element cannot rotate in view of its position depending on the impact of the crosswinds, so that a strong swirl of the crosswinds and a systematic deflection toward the bottom side is guaranteed at all times.

According to a further advantageous embodiment of the invention, means for avoiding a rotation of the element during the transport through the air by a helicopter or the like are provided. The crosswind deflection element can thus simply be lifted with a hook of a helicopter and securely be transported through the air to the installation site. Also in case the element is lifted with a crane, the rotation of the element is prevented. Means for preventing the rotation of the element during the transport through the air may, for example, be realized in the form of a protruding rod with a wind cone at its free end. The rod projects laterally from the crosswind deflection element and comprises at its end the wind cone so that the element remains in its respective position and cannot rotate in the air. Other means for preventing the rotation of the element during a transport through the air may also be provided.

According to a further advantageous embodiment of the invention, the length of the guide plates increases from the bottom upward up to approximately the double. That means, the length of the lowermost guide plate is approximately half the length of the uppermost guide plate. The surface for the systematic deflection of the impinging winds thus increases relatively strongly from the bottom upward, the crosswind deflection element according to the invention thus leading to an improved deflection, deviation and creation of swirls due to the above-mentioned nozzle effect. As a result, an even better prevention of deposits of solid material in the area and the vicinity of the crosswind deflection elements is guaranteed.

Further advantages, features and objects of the present invention will become apparent from the following description of embodiments. In the following, the invention will be described in more detail on the basis of embodiments and with reference to the attached drawings. In the drawings:

FIG. 1 is a perspective view of a crosswind deflection element of the invention according to a first embodiment of the invention;

FIGS. 2 a, 2 b are a side view and a plan view from above of the crosswind deflection element according to the first embodiment of FIG. 1;

FIG. 3 is a side view of an inventive crosswind deflection element according to a second embodiment; and

FIG. 4 is a side view of an inventive crosswind deflection element according to the second embodiment at the moment of the installation of the element.

A first embodiment of a crosswind deflection element 10 according to the invention as shown in different views in FIGS. 1, 2 a and 2 b will be explained in the following. The crosswind deflection element 10 is intended for an installation in the open country, a baseplate 1 at the bottom being provided at the lower end of the element 10 to this end. The baseplate 1 is here shown with four threaded pins that are screwed into respective holes with an internal screw thread and are screwed down for a fixation at a foundation (not shown) at the installation site or a counterplate. The crosswind deflection element 10 consists substantially of a central post 2, on which guide plates 3 protruding laterally and in a cruciform manner are mounted that serve for a systematic deflection and for the formation of swirls of winds impinging on the element 10. In this embodiment, the guide plates 3 are provided such that they project in a cruciform manner in four directions from the central post 2, while being mounted between upper cross members 4 and lower cross members 5. The length of the guide plates 3 is shorter in the lower area and increases continuously toward the upper side. Thus, the guide plates 3 form together four trapezoidal wind guide elements 30, respectively, as can in particular be taken from the side view of FIG. 2 a. These wind guide elements 30 are intended for systematically catching, swirling and deflecting the impinging crosswind downward into the area surrounding the crosswind deflection element 10 so that a deposit of solid material from the air, such as wind-borne sand or snow, can be prevented systematically. To this end, the length of the guide plates 3 of the wind guide elements 30 increases toward the upper side, thus creating some kind of nozzle effect in view of impinging winds, which swirls and routes the wind together with the solid material contained in the air toward the bottom without leading to an increased deposit around the crosswind deflection element 10. Thus, when a plurality of such crosswind deflection elements 10 is installed in the country at places susceptible to deposits (at crests or at mountain overhangs, for example), the generation of snow deposits, for example, can be prevented systematically. As a result, the formation of snow avalanches can effectively be prevented, as they are securely prevented with the invention even prior to the formation of undesired snow accumulations due to wind- and terrain-related conditions. Another field of application of such crosswind deflection elements is the prevention of sedimentation, i.e. a deposit of wind-borne sand in desert regions or coastal areas, for example. Also in this case, the crosswind deflection element serves for a systematic and effective prevention of deposits around the element 10 by catching and deflecting the crosswind by the four wind guide elements 30 protruding in a cruciform manner from the post 2, which are made up of a plurality of single guide plates 3. Other than in the case of conventional fences or barriers, no snow or sand deposits are formed on the lee side.

In the first embodiment shown in FIGS. 1, 2 a and 2 b, the guide plates 3 are mounted between upper and lower cross members 4, 5 in the form of square profiles by coupling ropes 9. The coupling ropes 9 are fixed at mounting flanges on the profiled tubes of the cross members 4, 5 and hold the respective guide plates 3 in their desired position and place. The guide plates 3, which can, for example, be made of a thin sheet metal, are respectively mounted at a distance to each other such that clearances of approximately half the width of the guide plates 3 are formed. Thus, the crosswind deflection element 10 is not completely solid, but is provided with clearances that allow a person to see through the elements. Furthermore, the clearances between the guide plates 3 are advantageous in that in case of very strong winds the elements 10 do not run the risk of being swept away or being damaged by the wind. In the first embodiment, the central post 2 projects somewhat over the upper cross members 4 that form the upper end of the wind guide elements 30. At the upper and lower cross members 4, 5, respective strut members 6, 7 are provided between the lower and the upper end of the post and approximately in the center of the cross members 4, 5. The strut members 6, 7, which can, for example, be realized in the form of tensible wire ropes or iron rods, increase the stability of the crosswind deflection element 10 without excessively increasing the overall weight. The strut members 6, 7 also serve for taking up the tensile stress applied by the coupling ropes 9, so that the wind guide elements 30 in the form of a kind of a sail can be stretched, the width increasing toward the upper side. In this embodiment, the four cross members 4, 5 protruding in a cruciform manner from the post 2 are also respectively mounted by mounting flanges and respective screw connections. However, the cross members can alternatively also be fixedly connected with the post 2, by a welding of metal pipes, for example. The detachable mounting by mounting flanges and screw connections is however advantageous in that the transport of the crosswind deflection elements 10 is facilitated and that less volume is necessary to this end. The crosswind deflection element 10 according to the invention is provided with comparatively large surfaces for deflecting and systematically routing the impinging winds. The guide plates 3 protruding in a cruciform manner into four directions guarantee a deposit of solid material from the air also in the case of changing wind directions. The wind can hit the crosswind deflection element 10 from all directions, without deposits of snow or sand, for example, being formed on the back side (lee side), as is the case with conventional fences or the like that are in the winter set up at the roadside of rural roads, for example, in order to prevent snowdrifts.

FIG. 3 shows in a side view a second embodiment of the crosswind deflection element 10 according to the invention. Contrary to the first embodiment described above, the guide plates 3 are here mounted by a circumferential frame 8, the frame 8 of the four wind guide elements 30 protruding in a cruciform manner being in this case mounted altogether on the central post 2 by respective mounting flanges and screw connections. The guide plates 3 are, for example, welded into the frame 8. Also here, respective upper and lower cross members 4, 5 are provided that form together with a somewhat thinner rod or profile the frames 8 at the ends of the guide plates 3. This form of the wind guide elements 30 is advantageous in that the single guide plates 3 are securely held together and fixed in their positions. FIG. 3 shows on the left-hand side and on the right-hand side, respectively, an alternative of this embodiment. While on the left-hand side of FIG. 3 a strut member 6 is only provided at the upper cross member 4 between the free end of the cross member 4 and the upper end of the post 2 and no lower strut member is provided, in the right-hand-side example an upper strut member 6 and a lower strut member 7 are—as in the first embodiment—provided that are fixed between the post 2 and approximately the center of the respective cross members 4, 5 and provide for additional stability. Alternatively, the strut members can be omitted—both in this embodiment and in the first embodiment. Also in this embodiment (FIG. 3), the guide plates 3 of the crosswind deflection element 10 are made of a comparatively thin sheet material. The sheet material can be provided with profiles or reinforcement ribs running in the longitudinal direction, so that the guide plates 3 are in spite of the comparatively thin material sufficiently stable to withstand varyingly strong wind conditions and provide the desired effect by swirling and deviating the wind downward in order to prevent sedimentation. Also in this case, the other members of the crosswind deflection element 10 can preferably be made of a metal material. In the embodiments shown, the central post 2 is realized as a round pipe. Alternatively, it may, however, also be realized as a rectangular pipe, as are the upper and lower cross members 4, 5 in these embodiments. Also here, the lower end of the post 2 is provided with a baseplate 1 that is reinforced by triangular reinforcement struts. The baseplate 1 has holes for a mounting via screw connections. The mounting situation of the crosswind deflection element 10 according to an embodiment of the invention on site is shown in a schematic side view of FIG. 4.

FIG. 4 shows a situation in which the crosswind deflection element 10 is carried through the air by a helicopter or a crane (not shown) shortly before it is put down at the desired position in the terrain. To this end, the upper end of the element 10 is fixed at a helicopter cargo hook 14. During the transport, the crosswind deflection element 10 is provided with a means 11 for preventing a rotation of the element 10 in the air, which is here shown in the form of a wind cone or a wind sleeve 11 that is mounted by a rod protruding laterally from the lower cross member 5. By providing such an anti-rotation means 11, the crosswind deflection element 10 is securely carried through the air and put down at the desired site in the terrain by a simple descent of the helicopter. For this purpose, a foundation plate 16 made of concrete was installed on the ground, on which a bottom plate 13 is mounted, onto which the member plate 12 of the baseplate 1 is placed. In order to facilitate the release and the installation of the crosswind deflection element 10, the bottom plate 13 is provided with a centrally arranged pipe socket 15, the diameter of which is somewhat smaller than the inner diameter of the central post 2. Thus, the two plates 12, 13 of the baseplate 1 can be placed on top of each other in the form of a plug-in system of the type pipe-in-pipe, so that the crosswind deflection element is directly upon release in the right position and secured from the beginning. Then, only a screw connection or another connection of the two plates 12, 13 of the baseplate 1 is required in order to guarantee a secure fixation of the free-standing crosswind deflection element 10. In this manner, no lateral anchoring means, such as anchor ropes, are required, as they are required with conventional snow fences or the like in order to guarantee an upright position also in the case of strong winds. The anti-rotation means 11 in the form of a wind cone guarantees that the element 10 is always aligned with the wind during transport, as illustrated by arrow W in FIG. 4. After the release and the fixation of the crosswind deflection element 10, the wind cone 11 is removed along with its fixation rod and can be reused for a further transport of another crosswind deflection element 10 of the same kind that is to be set up.

The invention provides an effective crosswind deflection element 10, which, over a large area, securely avoids a deposit of solid material from the air on this place as a result of the creation of swirls and the systematic redirection of the wind. The crosswind deflection element 10 according to the invention is, due to its construction with a plurality of comparatively thin guide plates 3, which project in a cruciform manner from a central post 2, very light in weight so that a transport via helicopter is rendered possible. The total weight of the crosswind deflection element 10 is preferably less than 550 kg. Furthermore, the crosswind deflection element 10 according to the invention requires only a comparatively small-scale intervention in natural environments, because the elements must only be set up at certain places in groups, respectively, and no large-scale building operations for the prevention of snow avalanches, debris avalanches or deposits of wind-borne sand are necessary. The invention is not limited to the embodiments illustrated above and can be modified in is various ways. In particular, the form of the guide plates may vary. In the embodiments illustrated above, the length of the lowermost guide plate 3 is approximately half the length of the uppermost guide plate 3, so that a comparatively strong enlargement of the wind guide elements 30 toward the upper side is given. Alternatively, the enlargement toward the upper side can also be less or more.

The guide plates 3 can be made of flat or profiled sheet metal, i.e. of relatively thin sheet metal, with reinforcing deformations in the longitudinal direction. However, the guide plates 3 may also be provided with reinforcing ribs, so that the high stability is guaranteed despite the lightweight construction. Also, the guide plates 3 may be fixed at the central post 2 by other means than by coupling ropes 9 or a circumferential frame 8 as shown in the illustrated embodiments. For example, the guide plates 3 may be mounted by retainer slots provided in the post 2 and by a fixed welding. Also, the distance of the guide plates 3 toward each other may be varied, for example to deliberately cause a higher permeability in certain areas: for example, the upper guide plates 3 may be mounted at larger spacings from each other than the lower guide plates 3 close to the ground, taking into account the stronger winds in the upper area. 

1. A crosswind deflection element for erection on open ground for the specific reduction or prevention of a deposit of snow, wind-borne sand or the like, with the element comprising: a baseplate at the bottom for anchoring into the ground, a central post rising up from the baseplate, and with a plurality of guide plates mounted on the post and projecting in vertical orientation in a cruciform manner on the post, the length of the guide plates increasing from the baseplate upward.
 2. The crosswind deflection element according to claim 1, wherein the guide plates are arranged at predetermined spacings from each other for the formation of permeable clearances.
 3. The crosswind deflection element according to claim 1, wherein the guide plates are at least at their free ends coupled to each other such that they form four sail-like wind guide elements that project in a cruciform manner from the post.
 4. The crosswind deflection element according to, further comprising: upper and lower cross members, which project from the post in a cruciform manner, for retaining the guide plates.
 5. The crosswind deflection element according to claim 1, wherein the baseplate is realized in a two-piece form, and is provided with an installation aid that is a plug-in system of the type pipe-in-pipe.
 6. The crosswind deflection element according to claim 1, wherein the guide plates or the wind guide elements formed of the guide plates are additionally secured to upper and/or lower strut members at upper and/or lower ends of the post.
 7. The crosswind deflection element according to claims 1, wherein the guide plates consist of sheets of a metal material that are longitudinally profiled or corrugated.
 8. The crosswind deflection element according to claim 1, wherein the guide plates are rigidly mounted in a circumferential frame that itself is attached to the post.
 9. The crosswind deflection element according to claim 1, wherein the guide plates are connected to each other and secured in their position by coupling ropes between upper and lower cross members.
 10. The crosswind deflection element according to claim 1, further comprising: an anti-rotation device for securing the element against rotation.
 11. The crosswind deflection element according to claim 1, further comprising: means for avoiding a rotation of the element during to the transport through the air by a helicopter or the like in the form of a detachably mountable wind cone that perpendicularly projects laterally from the post by a rod.
 12. The crosswind deflection element according to claim 1, wherein the length of the guide plates increases from the bottom upward up to approximately the double. 